This invention relates generally to devices which selectively prevent axial movement of a shaft. More specifically, the present invention relates to an apparatus and a method for utilizing a blocking pin to prohibit movement of the shaft in one direction along the shaft's axial dimension.
The use of blocking pins as safety devices is known in the art. Typically, potentially dangerous or damagable objects utilize blocking pins to prevent a movement of some portion of the object while the object is being handled or transported. The restriction of movement for a portion of the object lessens dangers associated with the object or the risk of damage to the object. Later, when the object is ready for service, the blocking pins may be removed to permit free movement of previously blocked portions of the object.
One known technique for utilizing blocking pins to prevent axial movement of a shaft makes opposing holes through walls of a sleeve that surrounds an end portion of the shaft. A blocking pin is then threaded through the opposing holes. The blocking pin is restrained by the surrounding sleeve. Thus, the blocking pin in conjunction with the sleeve blocks movement of the shaft past the blocking pin.
Although this technique works well in many applications, it exhibits problems which prevent its use in other applications. For example, the threading of a blocking pin through opposing holes in a sleeve may be a difficult and time consuming task under normal circumstances. This problem becomes exaggerated under adverse environmental conditions, such as darkness or cold weather where one may wear gloves while attempting to install the blocking pin. Additionally, in the above technique a sleeve must extend far enough away from the body of the object to allow sufficient access to the opposing holes so that the blocking pin may successfully be threaded. A high profile results, and the high profile may impede mounting the object into a machine which utilizes the object.